Your only quibble was no modular cabling. It would be interesting to see if the Nexus RX-5300, which has the same power rating and modular cables, also has the same acoustic profile.

At current US prices, the NX-5000 seems like a better deal than the Value 430. Only $10-20 more for a model that has the same or better efficiency and is as quiet or quieter in most scenarios and has more capacity and probably will last longer. I wonder if it will push down the price of the Value 430?

Nice PSU. Though the only reason to get it over the 430 would be if you're going to throw an HD 5970 and an overclocked i7 at it. Well that would be a reason.

if it is one thing I have learned about psu...
a small one can do big work, if you keep it from snapping out at a bare uncared for spot..most likely itself. bigger ones send a smidgen of bigger width, staying calmer.
the benefit of the smaller is staying in the efficiency range, warmer, less ripples, and a momentum to analogize a head of steam ... stable. Not may companines o there, saving themselves from expensive stuff. Therefore I am always leary of big watt psus...
I like to push boundaries just under recommendations of total power needed for this reason.

I do like the heatsinks in this one, they are inboard, not relying on the clear plastic to avoid the sides of its own casing.

other than that, not much new going on. The pull fan is a winner for me, I use atx reverse cooling standards, its all pull but a tiny low front fan forcing a compression gentle.

I have a strange problem with this PSU and I wonder if anyone else has experienced the same. The PSU is drawing 23W even when switched off from its own power switch. More about it in here: viewtopic.php?f=6&t=61292

Phelin -- That 26W sounds way too high. You should probably check with the vendor to see if it should be returned. iirc, I reported 0.7W with power switch off and 7.6W with the PSU on w/o any load. My sample is long gone, so have no way of checking this again, but I doubt my test gear or I would make a 25W error. I would certainly have discussed the anomaly in the text if it was seen in the testing.

I've been having similar issues with a Seasonic S12II-380, Seasonic X-650 and Enermax Modu87+. They all show between 15 and 25w when the PC is turned off. The same power meter shows 0w when I test it with a desk lamp.

This has all been with same mainboard. My electrically versed friend, whose power meter it is, told me either my computer really does draw that much when turned off and he said it would likely be a mainboard issue then, or the power meter, being a cheap consumer model, is just really inaccurate at very low wattages and misreads 2w as 20w.

I've been having similar issues with a Seasonic S12II-380, Seasonic X-650 and Enermax Modu87+. They all show between 15 and 25w when the PC is turned off. The same power meter shows 0w when I test it with a desk lamp.

This has all been with same mainboard.

It's most likely the motherboard. A simple check would be to plug any of those PSU's into another PC and measure the power draw when off.

I was thinking of getting one of these but then came across this review which is less than complimentary about it's Transient Response and DC Output Quality, which is confusing as the review on here doesn't mention any such problems.

Power supply reviews on SPCR focus on rough efficiency, acoustics and thermals. I don't believe the reviewers have any of the equipment necessary to do accurate (withing 0.1%) measurements, nor any of the other more fundamental power supply testing (transient test, crossload test, input and output noise characterisation). Like most products, you will need to consult multiple reviewers to get a complete picture.

At the moment there is no 'complete' reviewer on power supplies. Hardocp, jonnyguru and hardwaresecrets do a good job on formal testing, SPCR is more or less the only review site that knows how to properly do acoustic testing. Anandtech, X-bit labs and what other quality reviewers remain usually have more reference material and can tell you very well if a power supply is good value or not.

[hr]

Now, on the issue of incorrect displayed power: if it says it's using 20W when essentially off, you are probably using a power meter that cannot cope with bad power factors (you can recognize a 'better' (i'm purposely not saying 'good') consumer power meter if it's 'True RMS', displays fractions of a Watt and displays the power factor). If you're using a power meter that is not true RMS and/or only displays integer watt values, you can be very sure that your measurements are way off in low-load scenarios (hundreds of percents error can occur). Low load can be considered anything under 20W or less than 5% PSU load, whichever comes first.

Thanks. I know that SPCR is the only site worth consulting for acoustic testing, just didn't realise they are limited in terms of PSU electrical testing. I'll make sure I cross reference with those other sites you mention when considering PSU purchases in future.

Then again, couldn't SPCR check for such reviews and either not bother reviewing models that aren't up to scratch electrically, or if they still think they're worth considering regardless, warn of the problems at the end of the review and explain why they considered it to still be a viable option?

No doubt I'm going to be spending even more on PSUs now, when I find out all the "budget" quiet ones are rather dodgy electrically

doveman: Instead of looking at the conclusion, try to find out when the issues occur. For instance, if the reviewer finds something wrong with the PSU at 400 W load, and you're never going to use more than 200 W, then there's maybe not much of a problem.This is a general advice, I'm not referring to the review you linked to.

Good advice thanks, which might allow me to still buy a "budget" PSU in some circumstances, although I might still be too worried about overall quality/quality control if a 500W+ PSU shows problems at 400W and of course, if it's fairly likely one might be installing a new graphics card in the near->mid future that takes the system to 400W, it would be a bad investment really.

W/ regard to SPCR PSU testing, the only test mentioned by multiplexer that we don't and can't do is dynamic testing. Crossloading simply refers to the minimum required load on each of the main rails to keep the other rails in spec; we do this only for the 12V line by putting the lower lines at 1A. Output noise and ripple have been standard in all our tests for years... and I know of no one who measures input noise.

Addressing the question of the 5000 electrical performance, it is by now at least a 3 yr old design, and PSUs have had a very steep development curve in the past few years. I am sure there are many that perform better today. Then there's the issue of sample variance -- did the other testers get one slightly off the mark?

Finally, Nexus is not a PSU maker/designer like Seasonic, Delta, or Enermax but a re-brander like Corsair and Antec; my general take on their products is that they tend to be a step behind the state of the art but generally pretty good and always very quiet.

There's no question that the NX-5000 is very quiet. I think the only comparable product is the Enermax Pro87+ 500W, which is very hard to find and goes for over £100, compared to the 5000 at around £70. The RX-5300 is around £83, compared to the Enermax Modu87+ 500W at around £120. I'd really like to get a modular PSU but I'm reluctant to assume the RX-5300 will be as quiet as the NX-5000 unless SPCR tells me it is, so any chance of getting that tested?

Regarding the electrical quality, to quote the summary from HardOCP's review "Like their bigger brother the RX-6300, these two units have voltage regulation matched by few others and surpassed by almost none, to date. However, like the RX-6300 before them, the NX-5000 R3 and RX-5300 have a number of weaknesses that we just can't over look. The poor Transient Response that almost goes out of specification, the poorer than the "already just OK" RX-6300 DC Output Quality, low by-current-standards efficiency, and confusing support means that these units are passing but not close to award worthy products overall. For certain users these units will be perfect with their almost silent operation."

Now perhaps poor Transient Response and worse than just OK DC Output Quality aren't as bad as they sound (I'm no electrical expert) and I should certainly look for some other reviews to see what they found, but as these problems are common to three different models, I doubt sample variance can be blamed. Low by-current-standards efficiency is not something that would put me off a PSU though.

No comment on dynamic -- i mean transient -- response. I'm not even sure what that means in a computer PSU. I know in an audio amp, this can make an audible difference, but there is nothing in a computer which is so subtly demanding as a percussive musical peak that instantaneously jumps power demand by 100x (possible in music).

As for voltage regulation, you have to look at the actual numbers and the conditions which brought them on. hardocp mentions a max of +0.35v high on the 12v line and + 0.25 on the 5V line. The latter is at the limit of the ATX12V guideline, but the former is well w/in spec. I doubt very much that either of these characteristics by themselves would have any meaningful effect on computer performance when compared against a PSU with perfect DC regulation.

I've said this before: In general, PC power supplies today are far better than they need to be. Both manufacturers/brands and reviewers quibble over fine details to achieve product differentiation.

They say Transient Response, not Dynamic Response, which seems to refer to their Transient Load Testing results at the bottom of this page, briefly how the PSU responds to short duration loads, such as a RAID array spinning up or draw from a video card. They mention the disappointing results are quite common with these ATNG built units.

But as you say, this and the voltage regulation issues may not have any meaningful effect in practice.

You're implying one hell of a dangerous assumption here: that copying other people's testing criteria (or to be more precise, not trying different testing methods and criteria) is somehow preferred. I'll explain as I go along.

MikeC wrote:

W/ regard to SPCR PSU testing, the only test mentioned by multiplexer that we don't and can't do is dynamic testing. Crossloading simply refers to the minimum required load on each of the main rails to keep the other rails in spec; we do this only for the 12V line by putting the lower lines at 1A.

This is all you really need to test for computer PSUs specifically. It's kind of marginally interesting to know what the PSU does in other crossload patterns, but this rarely yields useful standard results (i.e. efficiency, regulation, ripple). However, something I have said many times on other related forums: not everything you test needs to be published. You should be playing around and trying weird load patterns if you for instance see that the noise characteristics change dramatically as you 'unbalance' the crossload further. Anyway,

Quote:

Output noise and ripple have been standard in all our tests for years... and I know of no one who measures input noise.

You do You measure power factor, which for electronic loads is an integral quantification of the input current distortion. Electrically, nowadays, the actual power factor actually isn't that interesting anymore. Also, the value of publishing the power factor without context is a source of confusion for many readers because it is kind of an abstract quantity. What is important though, is the input distortion as a function of frequency, i.e. the FFT of the input current waveform. Basically all power analyzers can display this, and this can reveal a lot about the input filter and PFC quality. That's what I mean about input noise. The same goes for output noise: it's really not that important to know what the peak values are, as is the shape of the FFT.

doveman wrote:

They say Transient Response, not Dynamic Response, which seems to refer to their Transient Load Testing results at the bottom of this page, briefly how the PSU responds to short duration loads, such as a RAID array spinning up or draw from a video card. They mention the disappointing results are quite common with these ATNG built units.

But as you say, this and the voltage regulation issues may not have any meaningful effect in practice.

They do! Transient response is one of the most important tests a manufacturer does for its power supplies, and something that is very strangely absent from reviews. I think this is because power supply reviewers generally don't come from either the science or engineering, but from the general hardware/journalist genre and as such do not know how manufacturers usually characterize their equipment.

Transient response is not 'dynamic' response, nor is it the response to macroscopically (i.e. disks spinning up) 'short' duration peaks. Transient response is the response to (1) an instantaneous step current increase, (2) a dirac-function (very peaked impulses) load pattern (3) a ramp current increase/decrease (i.e. constant dI/dt) and (4) turn-on/turn-off. Now, what is important to know about this is that when you do such a thing (for instance, suddenly go from 1 to 5A current draw) the output voltage does not stay the same, but it has a tendency to either overshoot (underdamped) or undershoot (overdamped), depending on the attainable current slope. In designing a power supply, it is absolutely critical to design these output filters such that they 'do' this properly. If you don't, and you have for instance a load that turns on and off at 20kHz, the voltage may keep under- and overshooting or even amplify this effect every time over, causing what is called an oscillating power supply. What is most important to note here is that in general, these overshoots and undershoots cause way more output voltage disturbance than the ripple at constant load. Especially when you're dealing with power supplies that already have appreciable ripple, try the transient load patterns. You'll see that they will end up out of spec. Also, good transient response is a marker for a good quality supply. Bad transient response is a good indicator of early failure (bad transient response is usually caused by underrated output capacitors, with high ESR causing a lot of self-heating under dynamic load conditions, causing overheating and early aging of the capacitors).

Even if all of this text doesn't seem that important to you, there is one big lesson in here. Transient response, the quality of filtering, the brand and quality of the components used and the topology used (these last things can usually only be determined by doing a full tear-down, refer to hardwaresecrets) are actually the classic, 'original' if you will, markers for power supply quality and suitability. Back in the day when power supplies weren't reviewed and just built, this is what the engineers would base their decisions upon. These are the areas that actually cost money and that indicate a significant R&D effort. Efficiency, up until recently, as well as acoustics weren't that important. The only thing engineers would look at was the longevity of the fan used and whether cooling was sufficient. I'm not saying that that was a particularly good thing in the industry, but I am saying that just because none of the other reviewers don't do it, those testing criteria aren't important. They are definitely more important to assessing power supply quality and performance than measuring output peak-to-peak ripple and line regulation - things that are actually structurally done wrong*.

I hope it's a bit more clear now why I said what I said. And yes, I am a power electronics engineer who makes and mods power supplies, I am sort of biased

* (1) Vpp is often measured with purely resistive load behind a ginormous low-esr capacitor bank. This hugely dampens ripple both due to the constant nature of the load and the dampening effect of the uncommonly large capacitor bank. When measuring ripple with a real-life load it is seldomly less than 20% higher. (2) line regulation is often measured with too thin wires (e.g. all 12V power goes through 2 EPS12V plugs) and in general measured at the wrong connector. This causes some reviewers to report very steep regulation ramps which are actually just caused by the resistance of the wires used. They also don't take into account the specification which says that the voltage drop at maximum conductor current can sag a certain amount more than the ATX spec itself.

Oh, by the way, this is in no way an insult to SPCR or SPCR's testing methodology, I intend what I write to be informative.

Last edited by multiplexer on Fri Jul 15, 2011 9:12 am, edited 1 time in total.

Thanks for explaining all that. I'll definitely cross-reference reviews when choosing a PSU then. I certainly don't want to spend £70+ on a poor-quality one that only comes with a 2-year warranty! Better to spend £100 or so on a good quality one with a 5-year warranty.

As I'm reading up on the birth of PSU reviews at HardOCP, JonnyGURU and Hardwaresecrets I find that everything I have said has really been said before many times over (wow, what a surprise). The following link is an interesting thread and a testament to how much in-depth knowledge (and frankly, nitpicking) you really need to have to meaningfully and in the end comprehensively test and review power supplies:

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